Seeing as this thread has become a general discussion on problems / scripts for loading extensions.....

Perhaps this is already done, but would it be possible to check whether a system is running with unionfs before executing the mkwritable script when a .dsl extension is selected for loading. So far as I understand having unionfs running would mean that mkwritable would not be required? This would make the unc & dsl extensions operate in the same manner when unionfs was running & (probably) remove the need for the unc extension type (could unc extensions not be made to load on legacy, non-unionfs, systems if the mkwritable script was executed?)

Unionfs is only available upon boot time.Once unionfs is in place, mkwriteable does an immediate exit and never runs even when called via a .dsl load..

Unionfs and mkwriteable are not equals, to do so would generate too many symlinks and therefore inode usage that many computers would report "out of memory". Unionfs is an overlay so much less inode usage. Before there was unionfs several attempts where made to increase the directories in mkwriteable only to find many machines exhausted their inodes.